The eavesdropping is completely legal, officials say, as long as inmates and visitors are given advance warning. A recorded message warns inmates of the monitoring.

That foreknowledge hasn't stopped detainees from discussing false court testimony and other illegal acts, such as illicit drug sales or witness intimidation, Monroe County District Attorney David Christine said.

"It's shocking that even knowing they're being recorded, they sometimes talk about how they're going to lie on the stand," Christine said. "Right now, my detectives sometimes spend hours at a time, two of them, working at one time" to review prison recordings.

ITT-DSI, which holds the contract for the prison phone system, is working with prison officials to develop specifications for the upgrade. It includes a new feature that will enable detectives to pick out key words from conversations — perhaps slang words for drugs, or threatening phrases — so they can quickly review the tapes without having to hear to every word.

The monitoring system will be expanded to include phone receivers used by inmates and visitors, who are separated by a glass partition during visits.

Once specifications are developed, ITT-DSI and other providers will be asked to submit bids to install and maintain the new monitoring system. The system should be in place this summer, officials said.

"We'll have it done by the end of June," said Director of Treatment Garry McFarland, the prison's current highest ranking administrator.

The only conversations off-limits are those between inmates and their attorneys. Inmates must submit their lawyer's phone numbers in advance to prison authorities.